well arguably it may be justified to worry about 3rd party  MCBs on supplies where the PSSC is > the breaker 6kA rating and we are relying on the annex ZA and discrimination with the company fuse,  but it is very hard to justify it for any item downstream of an MCB.

In my experience (German, mostly) the continentals are much more used to seeing time switches, contactors, bell transformers, indeed almost anything DIN mounting,  in the cabinet that is rather more complex than the UK idea of a consumer unit - indeed if you wanted to put such things in a UK consumer unit you would struggle to find a maker that did all the options you might like. This may mean that only MCBs are on buss, and there are a few loops of wire to other devices, but done well this is not an issue. It is also common to put a socket in there for test meter or clip lamp, so a quick voltages and Zs test does  not need any covers off.

I must say it is an approach that has some appeal.

Mike.

You need to know how close it is to tripping before it does. In the UK with exposed meter tails a sensitve current meter clamped around both tails to read only the difference can help reveal what is going on. 

Understand that the 45 A figure is the load current, but that is only part of the battle - the trip looks at the difference between L and N current, and when this exceeds the threshold (30mA for safety of life on 240V systems, but maybe 100mA or 300mA if there are more sensitive ones downstream). Basically if electrons go down one wire and a different number come back up the other, then the assumption is that some got off part way round and there is a fault, that worst case may involve a person between L and earth, and that should trip an automatic disconnection. In the UK you would only have use a single 30mA device for a small flat or a limited no of circuits, it would be more usual to divide the load up across more than one RCD or to have an RCBO per final circuit, as the more stuff you plug in, each with a natural leakage to earth of a mA or two the more likely is a no fault trip - the sort of thing you describe.
So firstly what other numbers are on that RCD, and are there others ? Then, how easy is it to get in and measure things?

Mike.

From what I gathered from the video, the Norwegian electrician said that they didn't have to do much by the way of live testing - just continuity and insulation resistance for new circuits. The live side - Ze - was down to the electricity supplier, although he did check RCD trip times.

Our main RCD (on the right of the image) will trip intermittently and we can't quite work out why.

Is it a simple RCD? I was under the impression that the first tier of RCD in France was typically EdF's device which is a combined 500mA RCD and load limiter, so unlike an ordinary RCD is prone to tripping on prolonged overload. I'd guess it'll have a thermal element in it rather like MCBs so will tend to be driven by the average load over a reasonable length of time rather than the exact load at the moment of tripping.

   - Andy.

edited to add:

https://uk.rs-online.com/web/p/mcbs/4820987

"Two-pole low voltage subscriber circuit breakers (for French blue tariff).

I love the little on/off stickers, which remind me of "stop" signs on the roads. Don't the French have their own words for on and off. "allumé", "éteint"?

My experience, as an engineer, is that some electricians can get stuck in their ways. Electricians follow instructions and follow rules much more than carrying out problem solving and innovation that engineers do all the time.

Electricians might think they know all there is to know about SPDs, but how many could develop such a device, or even determine that there is a good reason to have to develop such a device?!

In my locality it's tricky to find tradesmen who are very good when it comes to owner occupied houses that don't burn a hole in your bank account, unless it's just the bare minimum the owner asks for. Instead, they overwhelmingly have a mindset geared to rentals, so tend to concentrate on offering the bare minimum. How many rentals have solar panels or EV chargers? How many that don't have them have a CU set up to accommodate them?

So what do the electricians install as standard? A BG CU from Screwfix with provision for just 6 circuits, and no SPD unless the owner of the property specifically asks for one. If you want a 2 row box from Hager or Eaton installed, then expect to pay more than twice as much even if you supply all the parts and specify just 6 circuits at the outset with no fancy accessories, to have it installed by an electrician who is familiar with installing such devices. Most ordinary electricians will freak out at the sight of such consumer units, or ask a barrage of questions what you intend to put inside it, but more often than not take the advantage to charge more than twice as much as for the 6 circuit CU from Screwfix they usually install. If you want fancy accessories installed, then the electrician had probably never even seen such delights as a DIN rail mounted timeswitch before.

As I stated in the OP, it's only a metal box.

Crikey that's dissed all electricians then. I'm guessing you've had a bad experience recently Arran 

Do take care - I could say that in my experience as an experimental physicist specialising in solid state and electronics, some engineers are not so great either. We all have blind spots.

!!!

Mike

Well, there might be a bit of "monkey see, monkey do". It's really a matter of talking to the customer. If the customer is a large landlord, economy may be at the forefront, but that's their decision.

Isn't the real question, "what would I install for myself?"

I rather like the Schneider "wireless" RCBO boards which I have seen at a NAPIT event, but £1k is enough to make anybody's eyes water. On the other hand, that might just be a quarter's electricity bill, so why the heck not?

There's "monkey see, monkey do" in every profession...

A few years ago there was a big debate on this forum about wiring up ceiling lights, and whether many electricians do it according to what they previously encountered or learned in training courses rather than considered different (and better) alternatives.

Large landlords are one type of customer, but what I had in mind are small scale landlords who own just one or two houses, and more often than not just want things cheap and minimal with only the requirements of today and not tomorrow,